David Miller wrote:
From: Rick Jones <[EMAIL PROTECTED]>
Date: Thu, 30 Aug 2007 18:07:13 -0700
Anyhow, I'll try grubbing around the source code (already doing that to
see about writing a pet tcp cong module) but if pointers to the likely
relevant files were available I could try to help thrash-out the routing
metric version. Like I said the consumers of this are a triffle well,
"anxious" :)
The change is actually a lot simpler than the sysctl version.
In fact it borders on trivial :-)
Signed-off-by: David S. Miller <[EMAIL PROTECTED]>
diff --git a/include/linux/rtnetlink.h b/include/linux/rtnetlink.h
index c91476c..dff3192 100644
--- a/include/linux/rtnetlink.h
+++ b/include/linux/rtnetlink.h
@@ -351,6 +351,8 @@ enum
#define RTAX_INITCWND RTAX_INITCWND
RTAX_FEATURES,
#define RTAX_FEATURES RTAX_FEATURES
+ RTAX_RTO_MIN,
+#define RTAX_RTO_MIN RTAX_RTO_MIN
__RTAX_MAX
};
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index 9785df3..1ee7212 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -555,6 +555,16 @@ static void tcp_event_data_recv(struct sock *sk, struct
sk_buff *skb)
tcp_grow_window(sk, skb);
}
+static u32 tcp_rto_min(struct sock *sk)
+{
+ struct dst_entry *dst = __sk_dst_get(sk);
+ u32 rto_min = TCP_RTO_MIN;
+
+ if (dst_metric_locked(dst, RTAX_RTO_MIN))
+ rto_min = dst->metrics[RTAX_RTO_MIN-1];
+ return rto_min;
+}
+
/* Called to compute a smoothed rtt estimate. The data fed to this
* routine either comes from timestamps, or from segments that were
* known _not_ to have been retransmitted [see Karn/Partridge
@@ -616,13 +626,13 @@ static void tcp_rtt_estimator(struct sock *sk, const
__u32 mrtt)
if (tp->mdev_max < tp->rttvar)
tp->rttvar -= (tp->rttvar-tp->mdev_max)>>2;
tp->rtt_seq = tp->snd_nxt;
- tp->mdev_max = TCP_RTO_MIN;
+ tp->mdev_max = tcp_rto_min(sk);
}
} else {
/* no previous measure. */
tp->srtt = m<<3; /* take the measured time to be rtt */
tp->mdev = m<<1; /* make sure rto = 3*rtt */
- tp->mdev_max = tp->rttvar = max(tp->mdev, TCP_RTO_MIN);
+ tp->mdev_max = tp->rttvar = max(tp->mdev, tcp_rto_min(sk));
tp->rtt_seq = tp->snd_nxt;
}
}
At the risk of showing my ignorance (what me worry about that?-) I
presume this is then an interface expecting to take-in jiffies? That
means the user has to know the value of HZ which can be (IIRC) one of
three different values?
rick jones
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